The present invention relates in general to a hydraulic control circuit and in particular to a control device for a hydrostatic drive of the type including an adjustable pump, a pressure-responsive setting cylinder coupled to the pump, a hydraulic motor connected via working conduits to the pump and a measuring motor coupled to the hydraulic motor to operate with a proportional speed therewith and cooperating with flow volume adjusting means to generate a control flow for the hydraulic motor in order to regulate its rotary speed.
In prior-art control devices of this kind an adjustable throttle is arranged in the measuring circuit of the measuring motor, and as the hydraulic motor is adjustable by means of a setting cylinder which depending on the throughflow value fed by the adjustable throttle in the measuring circuit, is adjusted to the desired rotary speed. This known controlling device, however, does not take into consideration the behavior of the pump so that the field of application as well as the control accuracy of such prior-art devices are limited.